Echocardiography

Gale Encyclopedia of Surgery: A Guide for Patients and Caregivers

Echocardiography

Definition

Echocardiography is a diagnostic test that uses ultrasound waves to produce an image of the heart muscle and the heart's valves.

Purpose

Echocardiography is used to diagnose certain cardiovascular diseases, and is one of the most widely used diagnostic tests for heart disease. Ultrasound waves that rebound or echo off the heart can show the size, shape, and movement of the heart's valves and chambers, as well as the flow of blood through the heart. Echocardiography may show abnormalities such as a poorly functioning heart valve or damage to the heart tissue from a heart attack. Echocardiography is especially useful for assessing disorders of the heart valves. It not only allows doctors to evaluate the heart valves, but can also detect abnormalities in the pattern of blood flow. For example, echocardiography can show the backward flow of blood through heart valves that are partially open (that should be fully closed). This backward flow of blood through a valve is known as regurgitation. By assessing the motion of the heart wall, echocardiography can help detect the presence, and assess the severity, of coronary artery disease, as well as help determine whether chest pain is related to heart disease. Additionally, echocardiography can help detect hypertrophic cardiomyopathy, in which the walls of the heart thicken in an attempt to compensate for heart muscle weakness.

Echocardiography is also used to evaluate heart murmurs (abnormal heart sounds), determine the causes of congestive heart failure, assess enlarged hearts or hearts with septal defects (holes between pumping chambers), and monitor the heart in patients with diseases that may affect heart function (e.g., lupus, lung diseases). The biggest advantage to echocardiography is that it is noninvasive (it does not involve breaking the skin or entering body cavities) and has no known risks or side effects. Echocardiography is often used in conjunction with other diagnostic tests for the heart such as electrocardiography .

Echocardiography is usually performed in the cardiology department at a hospital, but may also be performed in a cardiologist's office or an outpatient imaging center. Because the ultrasound scanners used to perform echocardiography are portable (handheld) or mobile, echocardiography can be performed in the hospital's emergency department or at the bedside of patients who cannot be transported to the cardiology department.

Description

Echocardiography creates an image of the heart using ultra-high-frequency sound waves—sound waves that are too high in frequency to be heard by the human ear. The technique is very similar to ultrasound scanning commonly used to visualize the fetus during pregnancy.

An echocardiography examination generally lasts between 15–30 minutes. The patient lies bare-chested on an examination table. A special gel is spread over the chest to help the transducer make good contact and slide smoothly over the skin. The transducer, also called a probe, is a small handheld device at the end of a flexible cable. The transducer, essentially a modified microphone, is placed against the chest and directs ultrasound waves into the chest. Some of the waves get echoed (or reflected) back to the transducer. Since different tissues and blood reflect ultrasound waves differently, these sound waves can be translated into a meaningful image of the heart that can be displayed on a monitor or recorded on paper or tape. The patient does not feel the sound waves, and the entire procedure is painless.

Occasionally, variations of the echocardiography test are used. For example, Doppler echocardiography employs a special microphone that allows technicians to measure and analyze the direction and speed of blood flow through blood vessels and heart valves. This makes it especially useful for detecting and evaluating regurgitation through the heart valves. By assessing the speed of blood flow at different locations around an obstruction, it can also help to precisely locate the obstruction.

An exercise echocardiogram, or stress echo, is an echocardiogram performed during exercise, when the heart muscle must work harder to supply blood to the body. This allows doctors to detect heart problems that might not be evident when the body is at rest and needs less blood. For patients who are unable to exercise, certain drugs can be used to mimic the effects of exercise by dilating the blood vessels and making the heart beat faster.

During the examination the sonographer can take measurements and, using the ultrasound scanner's computer, make calculations, including measuring blood flow speed. Most ultrasound scanners are equipped with videotape recorders or digital imaging/archiving devices to record the real-time examination, and with medical image printers to print out hard copies of still images.

Preparation

The patient removes any clothing and jewelry above the chest.

Aftercare

No special measures need to be taken following echocardiography.

Risks

There are no known complications associated with the use of echocardiography. There is a slight risk of having a heart attack during an exercise echocardiogram, due to the stress put on the heart during the test, mostly for patients with a history of heart attack or other risk factors.

Normal results

A normal echocardiogram shows a normal heart structure and the normal flow of blood through the heart chambers and heart valves. However, a normal echocardiogram does not rule out the possibility of heart disease.

An echocardiogram may show a number of abnormalities in the structure and function of the heart, including:

• thickening of the wall of the heart muscle (especially the left ventricle)
• abnormal motion of the heart muscle
• blood leaking backward through the heart valves (regurgitation)
• decreased blood flow through a heart valve (stenosis)

Resources

books

the patient's book of medical tests. boston, new york city: houghton mifflin company, 1997.

periodicals

kosoff, george. "basic physics and imaging characteristics of ultrasound." world journal of surgery 24 (february 2000): 134–142.

lee, thomas h., and charles a. boucher. "noninvasive tests in patients with stable coronary artery disease." new england journal of medicine 344, no. 24 (june 14, 2001): 1840–6.

organizations

american college of cardiology. heart house. 9111 old georgetown road, bethesda, md 20814-1699. (800) 253-4636. <http://www.acc.org>.

american heart association national center. 7272 greenville avenue, dallas, tx 75231. (800) aha-usa1. <http://www.americanheart.org>.

american institute of ultrasound in medicine. 14750 sweitzer lane, suite 100, laurel, md 20707-5906. (301) 498-4100. <http://www.aium.org>.

american registry of diagnostic medical sonographers. 600 jefferson plaza, suite 360, rockville, md 20852-1150. (800) 541-9754. <http://www.ardms.org>.

american society of echocardiography. 1500 sunday drive, suite 102, raleigh, nc 27607. (919) 787-5181. <http://asecho.org>.

other

barasch, eddy. "why doctors use echocardiography." <http://www.thedoctorwillseeyounow.com/articles/heart/echo card_3/>.

Jennifer E. Sisk, MA Lee Shratter, MD

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